Title

Authors

Home Institution

University of Puget Sound

Publication Date

Fall 2010

Program Name

Tanzania-Zanzibar: Coastal Ecology and Natural Resource Management

Abstract

Coral reefs are considered keystone ecosystems due to their socioeconomic, ecological, and educational value. In Zanzibar, Tanzania, reefs provide income and a protein source for large portions of the population. Fish are reliant upon reefs as grounds for feeding, breeding, and nursing. Reefs are related to mangrove and seagrass ecosystems; the three ecosystems are interconnected in their functions of protecting biodiversity of coastal organisms, coastal erosion, and improving water quality. Coral reefs are also subject to degradation by both anthropogenic and natural causes. Predation is one example of natural degradation of coral. Six species of corallivores were studied to compare their population dynamics on Bawe and Chumbe Reefs, Zanzibar. Transect and quadrat analyses were performed in order to determine the relative density of each corallivore species. The Line Intercept Transect Method was employed in order to determine substrate distribution. Data was analyzed using 21 transects (1,260 m2) inside the MPA and 14 transects (840 m2) outside of the MPA. Triggerfish had a significantly higher mean outside the Chumbe MA compared to both Bawe and within the MPA. Butterflyfish had a significantly higher observed mean within the MPA compared to outside the MPA, which had a higher mean than Bawe. There was a positive correlation between the percent of live coral and number of butterflyfish. There was a significantly higher percentage of live coral cover at the Chumbe Island reef than Bawe Island. There was a significantly higher number of both Drupella and Coralliophila snails at Bawe Island than inside the Chumbe MPA. This suggests that the benefits obtained from the implementation of the MPA and removal of COTS from the Chumbe Island Reef may have aided in the increased live coral cover, but has not significantly impacted the corallivore fish species which reside there. This study contributes to the limited information of corallivore densities, especially in the Zanzibar archipelago and will provide a baseline for future studies on coral predation.